1. Field of the Invention
The present invention relates to organic glass having a high refractive index and excellent other physical properties and being suitable for materials of optical parts such as lenses and prisms.
2. Description of the Prior Art
In this description, as an example of optical parts, a lens is cited but the optical parts are not limited to it.
Organic glass has been noticed as lens materials for spectacles because of its lightweightness in comparison with inorganic glass, and organic glass comprising the polymer of diethylene glycol bis (allyl carbonate) (abbreviated as "CR-39" hereinafter), methyl methacrylate or the like has been used as the lens material. However, these kinds of organic glass have a refractive index of 1.49-1.50 which is lower than the refractive index of inorganic glass, for example, the one of white crown glass that is 1.523. When such organic glass is used as lens materials for correcting one's eyesight, the glass material becomes thick as compared with an inorganic glass material, so that the material loses its merit of lightweightness and becomes to have a bad appearance. The tendency of the organic glass material becomes stronger with the increasing dioptory of lens. Therefore, the organic glass seemed not always suitable as lense materials, in particular, as high powered lens materials for correcting one's eyesight.
To solve the problems of organic glass, high refractive index-organic glass employing a diallyl phthalate resin has been suggested. However, the organic glass is brittle and its transmissivity has come into questions, so that its performance as lens materials is insufficient.